The GNU Compiler Collection contains frontends for
C, C++, Objective-C, Fortran, Java, and Ada as
well as libraries for these languages. It is a
full-featured ANSI C compiler with support for K&R
C as well. GCC provides many levels of source code
error checking traditionally provided by other
tools (such as lint), produces debugging
information, and can perform many different
optimizations to the resulting object code.

Eric is a full featured Python and Ruby editor and IDE, written in Python. It is based on the cross platform Qt GUI toolkit, integrating the highly flexible Scintilla editor control. It is designed to be usable as an everyday quick and dirty editor as well as being usable as a professional project management tool, integrating many advanced features that Python offers the professional coder. Eric includes a plug-in system, which allows easy extension of the IDE functionality with plug-ins downloadable from the net. Current stable versions are Eric4 based on Qt4 and Python 2 and Eric5 based on Python 3 and Qt4.

Wing IDE is a software development environment for Python. It provides powerful editing, code intelligence, refactoring, testing, debugging, and search capabilities that reduce development and debugging time, cut down on coding errors, and make it easier to understand and navigate Python code.

The GNU Debugger (GDB) is a source-level debugger for C, C++, Java, Modula-2, and several other languages. It runs on GNU/Linux, the BSD's, and almost every major proprietary OS. GDB can debug programs running on the same machine as itself, or it can communicate over a network or serial line with a debugging stub on another machine; thus, it can be used for embedded and kernel debugging.

EDB (Evan's Debugger) is a Qt4 based binary mode
debugger with the goal of having usability on par
with OllyDbg. It uses a plugin architecture, so
adding new features can be done with ease. The
current release is for Linux, but future releases
will target more platforms.

strace is a useful diagnostic, instructional, and debugging tool. System administrators, diagnosticians, and troubleshooters will find it invaluable for solving problems with programs for which the source is not readily available.

TOra is a Toolkit for Oracle that helps the DBA or developer of a database application. It features an SQL worksheet with PL/SQL block parsing, a PL/SQL debugger and editor with syntax highlighting, a Schema browser, Unicode support, printing, and a full suite of DBA management tools.

oXygen is an XML editor that supports any XML
document, and works with XML Schemas, DTDs, Relax
NG schemas, and NRL Schemas. It has powerful
transformation support that allows you to edit
XSLT and XSL-FO documents and to obtain documents
in the desired output format (such as HTML, PS, or
PDF) with just one click. It also includes a
complete Subversion client, support for flattening
XML Schemata, an XML Schema instance generator,
integration with the X-Hive/DB, MarkLogic and
TigerLogic XML databases, editing actions on the
diagram, and a rename refactoring action.

U++ is a C++ cross-platform rapid application development suite focused on programmers' productivity without sacrificing runtime performance. Based on strictly deterministic design, it provides a viable alternative to garbage-collected platforms, even for business logic oriented problems.